The Forgotten Transportation Tiers

Posted on 9/26/2018 9:08:51 AM By Jim Swope

Understandably, the original equipment manufacturer (OEM) tends to be the primary focus when analyzing the automotive market (or the broader transportation markets) due to the sheer size and technical scope of OEM bonding requirements and its relatively large volume of adhesives and sealants usage.  However, by focusing predominately on OEM assembly – at the exclusion of other transportation subsegments such as Tier I, II, and III parts, components, and subcomponents, for example – we can overlook much of the innovation enabled by adhesives and sealants. 

Table 1: Joining Technologies Commonly used for Dissimilar Material Combinations

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Source:  Center for Automotive Research (CAR), 2017
*GM patented process
Al=aluminum, Mag = Magnesium, Comp = Polymer Composites, MIG = Metal Inert Gas Welding, TIG = Tungsten Inert Gas Welding

New, lighter materials that are used to build more energy efficient vehicles have rightfully received copious attention in the transportation value chain. Lightweighting often involves substrates that are conducive to an adhesive solution. Joining mixed materials, thinner gauge substrates, and preventing noise transmission, while also meeting the requirements of automated processes, are all strengths of adhesives that OEM’s fully utilize (see Table 1 comparing adhesives bonding to other joining methods).These same OEM bonding requirements apply to Tier manufacturing.

Tiers also have their own unique processing requirements: Bonding substrates for instant positioning prior to subsequent operations, for example, which is best achieved with quick-cure or high green strength adhesives. In a different manner (albeit with similar results) the instant positioning property is also useful for securing rear view camera lenses as well as setting and holding bearing retention in DC motors, mounting interior sensor modules to windshields (also known as windscreens), and gasketing fluid handling components. A resin-based adhesive system’s impact-absorbing characteristics were employed to protect fragile components like ferrite magnets and window glass at tier levels long before the phrase “crash resistant” became popular for its descriptive value and use in automotive body structures.

Various adhesive applications have either crossed over or have been innovated indirectly from other industries. The use of fiber optics, LEDs, touch screen displays, and myriad electronics and semiconductor  applications have all been enabled by adhesive technology. In defense applications, clear adhesives are a mainstay for a light transmission path or to ruggedize a viewable screen.

Figure 2:  Ford Motor Company recently filed a patent for an autonomous police car, according to an article in Inside Towers. Autonomous vehicles represent the most dramatic change in transportation since the Interstate Highway System, and their growth is tied directly to the deployment of more wireless infrastructure.

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Source:  Wireless Infrastructure Association (courtesy of

In fact, many types of adhesives are easy to customize with formulation additives, which has led to a customized formula’s new material properties beyond bonding. Customization has been the impetus for discovering new end uses, such as the thermal management of electronic components and the development of conductive adhesives for components that need to be assembled independent of soldering processes. Component and circuit protection have also crossed over from defense but often with unique needs for fuel resistance or rework. Gaskets and seals are unique in their evolution: early applications for bonding and dressing (coating for increased seal or easier release) have evolved into form-in-place/cure-in-place liquid gaskets that are easier to automate, cost less, reduce waste, and simplify inventory.The ability to foam some chemistries has increased functionality and related uses such as gap sealants and NVH tools.

Adhesives have long been used in the manufacturing of vehicle interior components, but their nature has changed over time. Both micro and macro environmental concerns have pushed suppliers in new directions while performance demands have increased. Eliminating VOCs (volatile organic compounds) is a front burner concern; vehicle cabin air quality is an emerging concern with competing regulations fighting for dominance while construction materials present bonding challenges. Those materials may dictate the core adhesive chemistry such as a hot melt or contact cement with properties that meet an application’s porosity, surface wetting and gap filling requirements.  Applications with exposure to high heat and moisture (and flexural forces) are better met by specific subsets such as HMPUR (hot melt applied polyurethane) or pre-applied films.

Meeting environmental challenges is not as simple as moving from solvent to water. Many water-based systems start with a solvent reduction of additives that are hydrophobic (not water miscible) and then are blended with water. Even the relatively small amount of solvent can push the formula over the VOC limit.

Tier suppliers are often serviced by distribution, which has both advantages and disadvantages.  Namely, a Tier manufacturer gains access to a variety of technologies and suppliers through the distribution channel, avoiding the “fitting square pegs in round holes” dilemma when a supplier has only one or two core technologies.

The trade-off of buying through a distribution channel, however, can be giving up the formulator’s deep product knowledge in exchange for a distributor’s broader knowledge of the market.  Supplying an adhesive usually requires a thorough understanding of every aspect of the bonding application and user’s in-plant processes.  Otherwise, you risk discovering too late in implementation–due to knowledge gaps–that there were better options than what was specified.

The specific processing needs of the Tier manufacturer can often be met through customizing or tailoring off-the-shelf adhesives products, which may also create value for other participants along the vehicle supply chain.

Jim Swope, The ChemQuest Group, Inc.

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